(a) Field of the Invention
The present invention relates to a support for use in electrophotographic sensitive plate, and particularly relates to a support which renders a sensitive plates superior in durability as well as half-tone reproducibility.
(B) Description of the Prior Art
Conventional sensitive plates for use in electrophotography have been prepared by forming a photosensitive layer of selenium deposited through vacuum evaporation on the surface of a conductive support, and as the material for said conductive support, such metals as aluminum, nickel and brass have been popular.
Besides, as a method of minimizing leakage of the electrical charge on the photosensitive layer while the photosensitive layer is not being subjected to radiation with active radiant rays, or reducing dark-decay, there has been proposed the provision of a barrier layer consisting of metal oxide between said conductive support and the photosensitive layer. Provision of this barrier layer is performed through the process comprising dipping a metal plate such as an aluminum plate in an alkaline or acid solution thereby to effect etching and cleaning of the surface of said metal plate, drying thereafter, and placing in a furnace having a temperature of 200.degree. C or more for more than 30 minutes thereby to oxidize the surface of the metal plate.
Also, there has been known a method of forming a barrier layer on the surface of a metal plate by applying glow discharge thereto (See Japanese Patent Open No. 5779/1971).
However, the former of the foregoing two methods is defective in that, inasmuch as the inside of the high-temperature furnace is under atmospheric conditions, there is a fear of impurities becoming attached to the surface of the metal plate or being generated at this stage of processing. Besides, according to this method, it is difficult to control the thickness of the barrier layer, so that when a sensitive plate is prepared by employing the resulting support, the residual electric potential becomes too much or the light-fatigue is apt to take place. Moreover, because of the treatment at a high temperature, the metal plate (including cylindrically shaped ones such as a metal drum) is apt to become deformed. While, in the case of the latter method, it not only requires expensive manufacturing equipment but also is unsuitable for mass production.